Conventional sound tracks for motion picture films directly record analog sound signals on the motion picture film. The present Applicant has already applied for patent for a technique of recording digital patterns in a digital sound track on a motion picture film to meet the demand for motion picture films with a higher sound quality (Japanese Patent Applications Nos. 3-222342 and 3-265001). Motion picture films have also been proposed in which the areas between the sprocket holes serve as recording areas for digital patterns representing the digital audio signals of plural channels (published International Patent Application No. WO 92/14239).
Motion picture film exhibitors have an increased requirement for motion picture sound reproduction with rich ambience. However it is difficult to reproduce stable audio signals from a motion picture film because of film weave and speed instability in the projector. In general, a motion picture projector cannot provide a playback accuracy as good as that achieved by an audio tape recorder. Hence it is desirable to represent the motion picture sound signals digitally to stabilize the reproduced sound signals. The present invention has been brought to completion under such background.